We will study erythromycin-resistant and wild-type strains of Bacillus subtilis. We will determine if there is a difference in methylation of 23S RNA between resistant and sensitive strains. We will attempt to convert sensitive ribosomes to resistant ribosomes by in vitro methylation. In addition, we will determine if various strains which are resistant to erythromycin during vegetative growth become sensitive to the drug during the sporulation or germination phase of cell differentiation.